#include <iostream>
#include <math.h>
#include <string.h>
using namespace std;


int main(){
	int n;
	cin>>n;
	int a[n];
	int sum;
	for(int i=0;i<n;i++){
		cin>>a[i];
		sum += a[i];
	}
	int dp[n+1][sum+1];
	memset(dp,-1,sizeof(dp));
	dp[0][0] = 0;
	for(int i=1;i<=n;i++)
		for(int j=0;j<=sum;j++)
//			dp[i][j] = max(dp[i-1][j],max(j+a[i-1] <= sum?dp[i-1][j+a[i-1]]:-1,j-a[i-1]>=0?(dp[i-1][j-a[i-1]]+a[i-1]!=-1?dp[i-1][j-a[i-1]]+a[i-1]:-1):(abs(j-a[i-1]) <= sum  &&  dp[i-1][abs(j-a[i-1])] != -1?dp[i-1][abs(j-a[i-1])]-abs(j-a[i-1])+a[i-1]:-1)));
			dp[i][j] = max(dp[i-1][j],max(j+a[i-1] <= sum?dp[i-1][j+a[i-1]]:-1,j-a[i-1]>=0?(dp[i-1][j-a[i-1]]!=-1?dp[i-1][j-a[i-1]]+a[i-1]:-1):(dp[i-1][a[i-1]-j] != -1?dp[i-1][a[i-1]-j]+j:-1)));  // 
//	for(int i=0;i<=n;i++){
//		for(int j=0;j<=sum;j++){
//			cout<<dp[i][j]<<" ";
//		}
//		cout<<endl;
//	}
	cout<<(dp[n][0]==0?-1:dp[n][0]);
	return 0;
}